99999999221 has 4 divisors (see below), whose sum is σ = 100371746700. Its totient is φ = 99628251744.

The previous prime is 99999999193. The next prime is 99999999227. The reversal of 99999999221 is 12299999999.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 37655402500 + 62344596721 = 194050^2 + 249689^2 .

It is a cyclic number.

It is not a de Polignac number, because 99999999221 - 2²⁶ = 99932890357 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (99999999227) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 185873336 + ... + 185873873.

It is an arithmetic number, because the mean of its divisors is an integer number (25092936675).

Almost surely, 2^99999999221 is an apocalyptic number.

It is an amenable number.

99999999221 is a deficient number, since it is larger than the sum of its proper divisors (371747479).

99999999221 is a wasteful number, since it uses less digits than its factorization.

99999999221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 371747478.

The product of its digits is 172186884, while the sum is 77.

The spelling of 99999999221 in words is "ninety-nine billion, nine hundred ninety-nine million, nine hundred ninety-nine thousand, two hundred twenty-one".